Keysight Technologies N9040B UXA Signal Analyzer Service Guide 53
Boot Up and Initialization Troubleshooting
Potential Problems During Boot Process
Is the +5.1V_STBY LED on the A7 Midplane board on?
If yes:
After verifying that the connections from the yellow front panel Standby
LED back to the A4 Processor board are not at fault, replace the A4
Processor board.
If not:
Replace the A6 Power Supply assembly.
Before replacing the power supply, verify the midplane and motherboard interconnects are
mechanically secure.